This invention relates to an exhaust port control valve for a two stroke engine and more particularly to an improved control valve assembly for a multiple cylinder engine.
It has been proposed to employ a control valve and supplemental exhaust port system for two cycle crankcase compression engines and particularly those operating on the diesel principal so as to permit lowering of the compression ratio under certain running conditions to improve performance. For example, the high speed performance of the engine can be improved by opening the supplemental exhaust ports and reducing the compression ratio. However, the operation of these exhaust control valves can be quite critical due to the extreme conditions under which they operate. This is particularly true in conjunction with multiple cylinder engines wherein a plurality of exhaust ports need be controlled. Although a convenient valve assembly may be provided that consists of a cylindrical valve element that is supported in a bore in a cylinder for controlling all of these ports, distortion of the cylinder due to heat and bolt down loadings of the cylinder head can give rise to erratic operation or valve sticking.
It is, therefore, a principal object of this invention to provide an improved exhaust control valve for a multiple cylinder.
It is a further object of this invention to provide an improved exhaust control system for a two cycle internal combustion engine wherein the valve can offer smooth and consistent operation.